Recovery of boron from unacidified salt lake brine by solvent extraction
with 2,2,4-trimethyl-1,3-pentanediol
Abstract
The recovery of boron from salt lake brine using
2,2,4-trimethyl-1,3-pentanediol was investigated. Factors affecting
boron recovery, including pH, concentrations of extractant and H3BO3,
phase ratio(O/A), and temperature, were investigated. Increasing pH
initially resulted in high extraction rate, but there was a limitation,
as further increasing pH resulted in rapid formation of B[OH]4-
having a low capacity to complex with TMPD, and therefore lower boron
extraction. Boron recovery increased as the TMPD and O/A increased. The
combination of pH <7, O/A=1 & n(TMPD/H3BO3)=2:1 was ideal for
boron recovery, resulting in extraction efficiency of
>85%. To investigate extraction mechanism, slope ratio
method was combined with Raman and infrared spectroscopy to characterize
the structure of complex. Furthermore, under optimal conditions, a
three-stage extraction and two-stage stripping process was performed,
resulting extraction and stripping efficiency were 97.12% and 88.98%,
respectively. The results reveal a promising strategy of boron recovery
from SL brine without acidification.